IQ DECLINE DURING CHILDHOOD AND ADULT PSYCHOTIC SYMPTOMS IN A COMMUNITY SAMPLE - A 19-YEAR LONGITUDINAL-STUDY

Objective: The goal of this study was to examine cognitive antecedents of psychosis by determining whether variability in IQ during childhoo d was predictive of psychotic symptoms in adulthood. Method: Deviant r esponder analyses were used to examine prospectively the relationship of IQ at ages 4 and 7 to psychotic symptoms at age 23 in 547 offspring from a community sample (National Collaborative Perinatal Project) th at was unselected for psychiatric illness. The authors compared three hypotheses: that 1) low IQ, 2) large IQ fluctuations regardless of dir ection, or 3) large IQ declines would predict the presence of adult ps ychotic symptoms. Results: The 10% of individuals with substantially l arger than expected IQ declines from age 4 to 7 had a rate of psychoti c, but not other psychiatric, symptoms at age 23 that was nearly seven times as high as the rate for other persons. Parental socioeconomic s tatus and IQ at age 7 also predicted adult psychotic symptoms. However , when IQ at age 7, Ie decline between ages 4 and 7, and socioeconomic status were all included in a logistic regression analysis, only IQ d ecline remained significant. Conclusions: There is art increased likel ihood of developing psychotic symptoms in adulthood for a subgroup of individuals with substantially greater than expected IQ declines durin g childhood. IQ decline is specific for psychotic symptoms, but follow -up assessment when the study participants are further into the age of risk will be necessary to determine specificity for schizophrenia. Th e authors discuss the implications of this early cognitive downturn fo r a neurodevelopmental view of schizophrenia.